In Evolution, I can hit 'CTL/i' to view remote content in a message, in Thunderbird I have to either authorize a sender (which would then allow ALL of their remote content to be displayed), or use the mouse to allow the content on individual messages (a key-click is SO much more convenient).

Please save me scrolling through pages of shortcuts and just let me know if there is a shortcut key for this function in Thunderbird. Having to use the mouse is a minor annoyance, but it is absolutely an annoyance when one moves over from Evolution.